Remove <TargetFramework> elements from csproj files

RemoveTargetFramework.cs

// removeTargetFramework.cs
// Usage:
//   dotnet run removeTargetFramework.cs -- [start-directory] [--dry-run|-n]
// Examples:
//   dotnet run removeTargetFramework.cs -- . --dry-run
//   dotnet run removeTargetFramework.cs -- ../src
//   dotnet run removeTargetFramework.cs -- ../src -n

using System;
using System.IO;
using System.Collections.Generic;

var argsSpan = args.AsSpan();

string startDirectory = Directory.GetCurrentDirectory();
bool dryRun = false;

if (argsSpan.Length > 0)
{
    for (int i = 0; i < argsSpan.Length; i++)
    {
        var arg = argsSpan[i];

        if (arg.Equals("--help", StringComparison.OrdinalIgnoreCase) ||
            arg.Equals("-h", StringComparison.OrdinalIgnoreCase) ||
            arg.Equals("/?"))
        {
            PrintUsage();
            return;
        }

        if (arg.Equals("--dry-run", StringComparison.OrdinalIgnoreCase) ||
            arg.Equals("-n", StringComparison.OrdinalIgnoreCase))
        {
            dryRun = true;
            continue;
        }

        // First non-option argument is treated as the start directory
        if (startDirectory == Directory.GetCurrentDirectory())
        {
            startDirectory = arg;
            continue;
        }

        Console.Error.WriteLine($"Unrecognized argument: {arg}");
        PrintUsage();
        return;
    }
}

if (!Directory.Exists(startDirectory))
{
    Console.Error.WriteLine($"Error: Directory does not exist: {startDirectory}");
    return;
}

Console.WriteLine($"Starting search in: {Path.GetFullPath(startDirectory)}");
Console.WriteLine(dryRun
    ? "Dry run mode: will only list files that would be modified."
    : "Live mode: matching <TargetFramework> lines will be removed.");
Console.WriteLine();

int filesScanned = 0;
int filesModified = 0;

foreach (var csprojFile in Directory.EnumerateFiles(startDirectory, "*.csproj", SearchOption.AllDirectories))
{
    filesScanned++;

    string[] lines;
    try
    {
        lines = File.ReadAllLines(csprojFile);
    }
    catch (Exception ex)
    {
        Console.Error.WriteLine($"Failed to read {csprojFile}: {ex.Message}");
        continue;
    }

    var newLines = new List<string>(lines.Length);
    bool removedAnyLine = false;

    foreach (var line in lines)
    {
        if (line.Contains("<TargetFramework>", StringComparison.OrdinalIgnoreCase) &&
            line.Contains("</TargetFramework>", StringComparison.OrdinalIgnoreCase))
        {
            // Drop this line
            removedAnyLine = true;
            continue;
        }

        newLines.Add(line);
    }

    if (!removedAnyLine)
    {
        // No <TargetFramework> line found in this file
        continue;
    }

    filesModified++;

    if (dryRun)
    {
        Console.WriteLine(csprojFile);
    }
    else
    {
        try
        {
            File.WriteAllLines(csprojFile, newLines);
            Console.WriteLine($"Updated: {csprojFile}");
        }
        catch (Exception ex)
        {
            Console.Error.WriteLine($"Failed to write {csprojFile}: {ex.Message}");
        }
    }
}

Console.WriteLine();
Console.WriteLine($"Scanned {filesScanned} *.csproj files.");
Console.WriteLine(dryRun
    ? $"Would modify {filesModified} file(s)."
    : $"Modified {filesModified} file(s).");

static void PrintUsage()
{
    Console.WriteLine("Remove <TargetFramework> line from .csproj files");
    Console.WriteLine();
    Console.WriteLine("Usage:");
    Console.WriteLine("  dotnet run removeTargetFramework.cs -- [start-directory] [--dry-run|-n]");
    Console.WriteLine();
    Console.WriteLine("Options:");
    Console.WriteLine("  start-directory   Root directory to search (defaults to current directory).");
    Console.WriteLine("  --dry-run, -n     Show which files would be changed without modifying them.");
    Console.WriteLine("  --help, -h        Show this help message.");
}